Lexus RX 450h 2010 Owner's Manual page 151

1-8. Safety information
Removing a child restraint installed with a seat belt
Child restraint systems with a top tether strap
STEP 1
STEP 2
150
Press the buckle release button
and fully retract the seat belt.
Secure the child restraint system
using a seat belt or the LATCH
anchors, and remove the head
restraint.
Open the anchor bracket cover,
latch the hook onto the anchor
bracket and tighten the top tether
strap.
Make sure the top tether strap is
securely latched.